thumb|Modular connectors, left to right:
A Registered Jack (RJ) is a standardized telecommunication network interface for connecting voice and data equipment to a service provided by a local exchange carrier or long distance carrier. After their invention at Bell Labs by 1973, the standard was first defined in the Universal Service Ordering Code (USOC) system of the Bell System in the United States for complying with the registration program for customer-supplied telephone equipment mandated by the Federal Communications Commission (FCC). In 1980, they were codified in title 47 of the Code of Federal Regulations Part 68. superseded by T1.TR5-1999. For this delegation, the FCC removed Subpart F from the CFR and added Subpart G. The ACTA derives its recommendations for terminal attachments from the standards published by the engineering committees of the Telecommunications Industry Association (TIA). ACTA and TIA jointly published the standard TIA/EIA-IS-968, replacing the CFR information.
TIA-968-A, the current version of that standard, by reference. With the publication of TIA-968-B, the connector descriptions have been moved to TIA-1096-A.
|-
| RJ12(C/W)
| 6P6C
| Establishes a bridged connection for one telephone line with key telephone system control ahead of line circuit
|-
| RJ13(C/W)
| 6P4C
| Similar to RJ12, but behind the line circuit
|-
| RJ14(C/W)
| 6P4C
| For two telephone lines (6P6C if power on third pair)
|-
| RJ15C
| 3-pin weatherproof
| For one telephone line for boats in marinas
|-
| RJ18(C/W)
| 6P6C
| For one telephone line with make-busy arrangement
|-
| RJ21X
| 50-pin
| Multiple (up to 25) line bridged T/R configuration
|-
|
| 6P6C
| For three telephone lines
|-
| RJ26X
| 50-pin
| For multiple data lines, universal
|-
| RJ27X
| 50-pin
| For multiple data lines, programmed
|-
| RJ31X
| 8P8C
| Allows an alarm system to seize the telephone line to make an outgoing call during an alarm. The jack is placed closer to the network interface than all other equipment, and only four conductors are used.
|-
| RJ32X
| 8P8C
| Like RJ31X, this wiring provides a series tip and ring connection through the connecting block, but is used when the customer premises equipment is connected in series with a single station, such as an automatic dialer.
|-
| RJ33X
| 8P8C
| This wiring provides a series tip and ring connection of a KTS line ahead of the line circuit because the registered equipment requires CO/PBX ringing and a bridged connection of the A and A1 lead from behind the line circuit. Tip and ring are the only leads opened when the CPE plug is inserted. Typical usage is for customer-provided automatic dialers and call restrictors.
|-
| RJ34X
| 8P8C
| Similar to RJ33X, but all leads are connected behind the line circuit.
|-
| RJ35X
| 8P8C
| This arrangement provides a series tip and ring connection to whatever line has been selected in a key telephone set plus a bridged A and A1 lead.
|-
| RJ38X
| 8P4C
| Similar to RJ31X, with a continuity circuit. If the plug is disconnected from the jack, shorting bars allow the phone circuit to continue to the site phones. Only 4 conductors are used.
|-
| RJ41S
| 8P8C, keyed
| For one single-pair data line, universal (fixed loop loss and programmed)
|-
| RJ45S
| 8P8C, keyed
| For one single-pair data line, with programming resistor
|-
| RJ48C
| 8P4C
| For a four-wire data line (DSX-1)
|-
| RJ48S
| 8P4C, keyed
| For a four-wire data line (DDS)
|-
| RJ48X
| 8P4C with shorting bar
| For a four-wire data line (DS1)
|-
| RJ49C
| 8P8C
| For ISDN BRI via NT1
|-
| RJ61X
| 8P8C
| For four telephone lines
|-
| RJ71C
| 50-pin
| 12-line series connection using 50-pin connector (with bridging adapter) ahead of customer equipment. Mostly used for call sequencer equipment.
|}
Many of the basic names have suffixes that indicate subtypes:
- C: flush-mount or surface mount
- F: flex-mount
- W: wall-mount
- L: lamp-mount
- S: single-line
- M: multi-line
- X: complex jack
For example, RJ11 comes in two forms: RJ11W is a jack from which a wall telephone can be hung, while RJ11C is a jack designed to have a cord plugged into it. A cord can be plugged into an RJ11W as well.
RJ11, RJ14, RJ25 wiring
<!-- RJ11, RJ14, and RJ25 redirect here. -->
All of these registered jacks are described as containing a number of potential contact positions and the actual number of contacts installed within these positions. RJ11, RJ14, and RJ25 all use the same six-position modular connector, thus are physically identical except for the different number of contacts (two, four and six respectively) allowing connections for one, two, or three telephone lines respectively.
A cord connecting to an RJ11 interface requires a 6P2C connector. Nevertheless, cords sold as RJ11 often use 6P4C connectors (six position, four conductor) with four wires. Two of the six possible contact positions connect tip and ring, and the other two conductors are unused.
The conductors other than the two central tip and ring conductors are in practice variously used for a second or third telephone line, a ground for selective ringers, low-voltage power for a dial light, or for anti-tinkle circuitry to prevent pulse-dialing phones from sounding the bell on other extensions.
Pinout
The pins of the 6P6C connector are numbered 1 to 6, counting left to right when holding the cord entrance facing the viewer with the connector tab down.
Provisioning of power
Some telephones such as the Western Electric Princess and Trimline telephone models require additional power (~6 V AC) for operation of the incandescent dial light. This power is delivered to the telephone set from a transformer by the second wire pair (pins 2 and 5) of the 6P4C connector.
RJ21
{| style="float: right;"
| style="vertical-align: text-top;" | left|80px|thumb|Female RJ21 connector. Pin assignment is coordinated with the table. ||
{| class="wikitable" style="float: right; margin-left: 1.5em; margin-right: 0; margin-top: 0;"
|+ Even-count color code
! Color
! Pin<br/>(tip)
!
! Pin<br/>(ring)
! Color
|-
| 37px White/blue
| 26
|
| 1
| 37px Blue/white
|-
| 37px White/orange
| 27
|
| 2
| 37px Orange/white
|-
| 37px White/green
| 28
|
| 3
| 37px Green/white
|-
| 37px White/brown
| 29
|
| 4
| 37px Brown/white
|-
| 37px White/slate
| 30
|
| 5
| 37px Slate/white
|-
| 37px Red/blue
| 31
|
| 6
| 37px Blue/red
|-
| 37px Red/orange
| 32
|
| 7
| 37px Orange/red
|-
| 37px Red/green
| 33
|
| 8
| 37px Green/red
|-
| 37px Red/brown
| 34
|
| 9
| 37px Brown/red
|-
| 37px Red/slate
| 35
|
| 10
| 37px Slate/red
|-
| 37px Black/blue
| 36
|
| 11
| 37px Blue/black
|-
| 37px Black/orange
| 37
|
| 12
| 37px Orange/black
|-
| 37px Black/green
| 38
|
| 13
| 37px Green/black
|-
| 37px Black/brown
| 39
|
| 14
| 37px Brown/black
|-
| 37px Black/slate
| 40
|
| 15
| 37px Slate/black
|-
| 37px Yellow/blue
| 41
|
| 16
| 37px Blue/yellow
|-
| 37px Yellow/orange
| 42
|
| 17
| 37px Orange/yellow
|-
| 37px Yellow/green
| 43
|
| 18
| 37px Green/yellow
|-
| 37px Yellow/brown
| 44
|
| 19
| 37px Brown/yellow
|-
| 37px Yellow/slate
| 45
|
| 20
| 37px Slate/yellow
|-
| 37px Violet/blue
| 46
|
| 21
| 37px Blue/violet
|-
| 37px Violet/orange
| 47
|
| 22
| 37px Orange/violet
|-
| 37px Violet/green
| 48
|
| 23
| 37px Green/violet
|-
| 37px Violet/brown
| 49
|
| 24
| 37px Brown/violet
|-
| 37px Violet/slate
| 50
|
| 25
| 37px Slate/violet
|}
|-
|}
RJ21 is a registered jack standard using a micro ribbon connector with contacts for up to fifty conductors. It is used to implement connections for up to 25 lines, or circuits that require many wire pairs, such as used in the 1A2 key telephone system. The miniature ribbon connector of this interface is also known as a 50-pin telco connector, CHAMP(AMP), or Amphenol connector, the last being a genericized trademark, as Amphenol was a prominent manufacturer of these at one time.
A cable color scheme, known as even-count color code, is determined for 25 pairs of conductors as follows: For each ring, the primary, more prominent color is chosen from the set blue, orange, green, brown, and slate, in that order, and the secondary, thinner stripe color from the set of white, red, black, yellow, and violet colors, in that order. The tip conductor color scheme uses the same colors as the matching ring but switches the thickness of the primary and secondary colored stripes. Since the sets are ordered, an orange (color 2 in its set) with a yellow (color 4) is the color scheme for the 4·5 + 2 − 5 = 17th pair of wires. If the yellow is the more prominent, thicker stripe, then the wire is a tip conductor connecting to the pin numbered 25 + the pair #, which is pin 42 in this case. Ring conductors connect to the same pin number as the pair number.
A conventional enumeration of wire color pairs then begins blue (and white), orange (and white), green (and white) and brown (and white), which subsumes a color-coding convention used in cables of 4 or fewer pairs (8 wires or less) with 8P and 6P connectors.
Dual 50-pin ribbon connectors are often used on punch blocks to create a breakout box for private branch exchange (PBX) and other key telephone systems.
RJ45S
thumb|upright|8P8C keyed female connector (jack), the same as that used in RJ45S
The RJ45S, an obsolete standard jack once specified for modem or data interfaces, has a slot on one side to allow mating with a special variation of the 8P plug: a mechanically-keyed plug with an extra tab on one side that prevents it from mating with regular (non-keyed) 8P jacks. The visual difference from the more-common 8P female is subtle. The RJ45S keyed 8P modular connector has only pins 5 and 4 wired for tip and ring (respectively) of a single telephone line, and a "programming" resistor connected to pins 7 and 8.
RJ48
{| class="wikitable floatright"
|+ RJ48C and RJ48X wiring
! Pin !! Pair !! Signal
! width=160 | Color
|-
| 1 || R || RX ring
| 37px Orange/white
|-
| 2 || T || RX tip
| 37px White/orange
|-
| 3 || || Reserved
| 37px White/green
|-
| 4 || R1 || TX ring
| 37px Blue/white
|-
| 5 || T1 || TX tip
| 37px White/blue
|-
| 6 || || Reserved
| 37px Green/white
|-
| 7 || || Shield
| 37px White/brown
|-
| 8 || || Shield
| 37px Brown/white
|}
RJ48 is used for T1 and ISDN termination, local-area data channels, and subrate digital services. It uses the eight-position modular connector (8P8C).
RJ48C is commonly used for T1 circuits and uses pin numbers 1, 2, 4 and 5.
RJ48X is a variation that contains shorting blocks in the jack for troubleshooting: With no plug inserted, pins 2 and 5 (the two tip wires) are connected to each other, and likewise 1 and 4 (ring), creating a loopback so that a signal received on one pair is returned on the other. Sometimes this is referred to as a self-looping jack.
RJ48S is typically used for local-area data channels and subrate digital services and carries one line. It accepts a keyed variety of the 8P modular connector.
RJ48 connectors are fastened to shielded twisted pair (STP) cables, not the unshielded twisted-pair (UTP) commonly used in other installations.
RJ61
{| class="wikitable floatright"
|+ RJ61 wiring (USOC)
! Pin !! Pair !! Signal
! width=160 | Color
|-
| 1 || 4 || Tip
| 37px White/brown
|-
| 2 || 3 || Tip
| 37px White/green
|-
| 3 || 2 || Tip
| 37px White/orange
|-
| 4 || 1 || Ring
| 37px Blue/white
|-
| 5 || 1 || Tip
| 37px White/blue
|-
| 6 || 2 || Ring
| 37px Orange/white
|-
| 7 || 3 || Ring
| 37px Green/white
|-
| 8 || 4 || Ring
| 37px Brown/white
|}
RJ61 is a physical interface that was often used for terminating twisted pair cables. It uses an eight-position, eight-conductor (8P8C) modular connector.
This wiring pattern is for multi-line analog telephone use only; RJ61 is unsuitable for use with high-speed data because the pins for pairs 3 and 4 are too widely spaced for high signaling frequencies. T1 lines use another wiring for the same connector, designated RJ48. Ethernet over twisted pair (10BASE-T, 100BASE-TX and 1000BASE-T) also uses different wiring for the same connector, either T568A or T568B. RJ48, T568A, and T568B are all designed to keep both wires of each pair close together.
The flat eight-conductor silver-satin cable conventionally used with four-line analog telephones and RJ61 jacks is also unsuitable for use with high-speed data. Twisted pair cabling is required for data applications. Twisted-pair patch cable typically used with common Ethernet and other data network standards is not compatible with RJ61, because RJ61 pairs 3 and 4 would each be split across two different twisted pairs in the patch cable, causing excessive cross-talk between voice lines 3 and 4, with conversations on each line literally being audible on the other.
With the advent of structured wiring systems and TIA/EIA-568 (now ANSI/TIA-568) conventions, the RJ61 wiring pattern is falling into disuse. The T568A and T568B standards are used in place of RJ61 so that a single wiring standard in a facility can be used for both voice and data.
Similar jacks and unofficial names
The following RJ-style names do not refer to official ACTA types.
The labels RJ9, RJ10, RJ22 are variously used for 4P4C and 4P2C modular connectors, most typically installed on telephone handsets and their cordage. Telephone handsets do not connect directly to the public network, and therefore have no registered jack designation.
RJ11 generally uses 6P2C, but can also be 6P4C if powered.
RJ45 is often incorrectly used when referring to an 8P8C connector used for ANSI/TIA-568 T568A and T568B and Ethernet. The connector commonly used for twisted-pair Ethernet is a non-keyed 8P8C connector, quite distinct from that used for RJ45S. The plug used for RJ45S is both mechanically and electrically incompatible with any Ethernet port: it cannot fit into an Ethernet port, and it is wired in a way that is incompatible with Ethernet. The new ARJ45 interface, however, is a plug and jack allowing higher transmission rates, and the jack can, optionally, be backward-compatible with the common 8P8C plugs of Gigabit Ethernet and earlier standards.
RJ50 is often a 10P10C interface, often used for data applications.
The micro ribbon connector, first made by Amphenol, that is used in the RJ21 interface, has also been used to connect Ethernet ports in bulk from a switch with 50-pin ports to a Cat-5 rated patch panel, or between two patch panels. A cable with a 50-pin connector on one end can support six fully wired 8P8C connectors or Ethernet ports on a patch panel with one spare pair. Alternatively, only the necessary pairs for 10/100 Ethernet can be wired allowing twelve Ethernet ports with a single spare pair.
This connector is also used with spring bail locks for SCSI-1 connections. Some computer printers use a shorter 36-pin version known as a Centronics connector.
The 8P8C modular jack was chosen as a candidate for ISDN systems. In order to be considered, the connector system had to be defined by an international standard, leading to the creation of the ISO 8877 standard. Under the rules of the IEEE 802 standards project, international standards are to be preferred over national standards, so when the original 10BASE-T twisted-pair wiring version of Ethernet was developed, this modular connector was chosen as the basis for IEEE 802.3i-1990.
See also
- Audio and video interfaces and connectors generic article
- BS 6312 British equivalent to RJ25
- EtherCON ruggedized 8P8C Ethernet connector
- Key telephone system
- Modified Modular Jack a variation used by Digital Equipment Corporation for serial computer connections, and also for CEA-909 antennas.
- Protea (telephone) South African telephone jack standard
- Telecommunications Industry Association Standards Developing Organization for ACTA
References
External links
- RJ glossary
- ANSI/TIA-968-B documents of FCC specifications from the Administrative Council for Terminal Attachments, section 6.2 in particular
- ANSI/TIA-1096-A
- Administrative Council for Terminal Attachments
- Doing your own telephone wiring
- Connecting a second phone line